Reduced hydroperoxidase (HPI and HPII) activity in the Δfur mutant contributes to increased sensitivity to UVA radiation in Escherichia coli

Hoerter, James D.; Arnold, Alan A.; Ward, Christopher; Sauer, Michael; Johnson, Steve; Fleming, Todd J.; Eisenstark, A.

doi:10.1016/j.jphotobiol.2005.01.003

Cited by 33 publications

(25 citation statements)

References 26 publications

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“…Positive regulation of catalase-encoding genes by Fur has been reported previously. In E. coli, HPI catalase activity is increased in the presence of iron in a Fur-dependent manner, and Fur is responsible for increased levels of HPII catalase activity at stationary phase (5,21,69). In Staphylococcus aureus, a fur mutation results in decreased catalase activity through a decrease in katG transcription (22).…”

Section: Resultsmentioning

confidence: 99%

Regulation of Catalase-Peroxidase KatG Is OxyR Dependent and Fur Independent in Caulobacter crescentus

et al. 2011

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Most organisms that grow in the presence of oxygen possess catalases and/or peroxidases, which are necessary for scavenging the H 2 O 2 produced by aerobic metabolism. In this work we investigate the pathways that regulate the Caulobacter crescentus katG gene, encoding the only enzyme with catalase-peroxidase function in this bacterium. The transcriptional start site of the katG gene was determined, showing a short 5 untranslated region. The katG regulatory region was mapped by serial deletions, and the results indicate that there is a single promoter, which is responsible for induction at stationary phase. An oxyR mutant strain was constructed; it showed decreased katG expression, and no KatG protein or catalase-peroxidase activity was detected in stationary-phase cell extracts, implying that OxyR is the main positive regulator of the C. crescentus katG gene. Purified OxyR protein bound to the katG regulatory region between nucleotides ؊42 and ؊91 from the transcription start site, as determined by a DNase I footprinting assay, and a canonical OxyR binding site was found in this region. Moreover, OxyR binding was shown to be redox dependent, given that only oxidized proteins bound adjacent to the ؊35 sequence of the promoter and the katG P1 promoter was activated by OxyR in an H 2 O 2 -dependent manner. On the other hand, this work showed that the iron-responsive regulator Fur does not regulate C. crescentus katG, since a fur mutant strain presented wild-type levels of katG transcription and catalase-peroxidase production and activity, and the purified Fur protein was not able to bind to the katG regulatory region.

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Section: Resultsmentioning

confidence: 99%

Regulation of Catalase-Peroxidase KatG Is OxyR Dependent and Fur Independent in Caulobacter crescentus

et al. 2011

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“…The mechanism of inactivation by UVA light is still not fully understood. Recent studies suggest that UVA light mediates its biological effects primarily via oxidative mechanisms that lead to reactive oxygen species (21).…”

Section: Discussionmentioning

confidence: 99%

Specific Growth Rate Determines the Sensitivity of Escherichia coli to Thermal, UVA, and Solar Disinfection

Berney

Weilenmann

Ihssen

et al. 2006

Appl Environ Microbiol

208

160

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Knowledge about the sensitivity of the test organism is essential for the evaluation of any disinfection method. In this work we show that sensitivity of Escherichia coli MG1655 to three physical stresses (mild heat, UVA light, and sunlight) that are relevant in the disinfection of drinking water with solar radiation is determined by the specific growth rate of the culture. Batch-and chemostat-cultivated cells from cultures with similar specific growth rates showed similar stress sensitivities. Generally, fast-growing cells were more sensitive to the stresses than slow-growing cells. For example, slow-growing chemostat-cultivated cells (D ‫؍‬ 0.08 h ؊1 ) and stationary-phase bacteria from batch culture that were exposed to mild heat had very similar T 90 (time until 90% of the population is inactivated) values (T 90, chemostat ‫؍‬ 2.66 h; T 90, batch ‫؍‬ 2.62 h), whereas T 90 for cells growing at a of 0.9 h ؊1 was 0.2 h. We present evidence that the stress sensitivity of E. coli is correlated with the intracellular level of the alternative sigma factor RpoS. This is also supported by the fact that E. coli rpoS mutant cells were more stress sensitive than the parent strain by factors of 4.9 (mild heat), 5.3 (UVA light), and 4.1 (sunlight). Furthermore, modeling of inactivation curves with GInaFiT revealed that the shape of inactivation curves changed depending on the specific growth rate. Inactivation curves of cells from fast-growing cultures ( ‫؍‬ 1.0 h ؊1 ) that were irradiated with UVA light showed a tailing effect, while for slow-growing cultures ( ‫؍‬ 0.3 h ؊1 ), inactivation curves with shoulders were obtained. Our findings emphasize the need for accurate reporting of specific growth rates and detailed culture conditions in disinfection studies to allow comparison of data from different studies and laboratories and sound interpretation of the data obtained.

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“…Some bacterial species, like Yersinia pestis (59), S. aureus (78), and P. aeruginosa (74), also utilize Fur to activate kat expression. E. coli fur mutants are more susceptible to UVA irradiation oxidative damage due to decreased production of the hydroperoxidases (HPI and HPII) (75). The neutrophil activating protein (napA), which helps to protect H. pylori from oxidative damage, is suspected to be under the control of Fur (28,94,102).…”

Section: Fur and Oxidative Stressmentioning

confidence: 99%

This Is Not Your Mother's Repressor: the Complex Role of Fur in Pathogenesis

2009

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Reduced hydroperoxidase (HPI and HPII) activity in the Δfur mutant contributes to increased sensitivity to UVA radiation in Escherichia coli

Cited by 33 publications

References 26 publications

Regulation of Catalase-Peroxidase KatG Is OxyR Dependent and Fur Independent in Caulobacter crescentus

Regulation of Catalase-Peroxidase KatG Is OxyR Dependent and Fur Independent in Caulobacter crescentus

Specific Growth Rate Determines the Sensitivity of Escherichia coli to Thermal, UVA, and Solar Disinfection

This Is Not Your Mother's Repressor: the Complex Role of Fur in Pathogenesis

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